By Aya Elamroussi, CNN The Delta variant continues to be a major threat to America’s fight against the Covid-19 pandemic and getting more vaccine shots into arms is a way to combat it, an expert says. The highly contagious, aggressive variant was first detected in India and has made its way to the majority of US states, officials said. In Washoe County, Nevada, for instance, 17 Delta variant cases have been detected, the county’s Regional Information Center said in a press release. Two of the Delta variant cases involve students at Hunsberger Elementary School. “We cannot continue to have pockets of unvaccinated counties and areas in this country,” Dr. Jayne Morgan, executive director of Piedmont Healthcare’s Coronavirus Task Force in Atlanta, told CNN’s Fredricka Whitfield Saturday. Those pockets of unvaccinated populations create a place where variants can continue to develop, “and then those mutations have the ability to continue to learn, to become smarter, and eventually evade the immunization status of the rest of us,” Morgan said.